Date of Award

12-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Forestry and Natural Resources

First Advisor

Robert K. Swihart

Committee Chair

Robert K. Swihart

Committee Member 1

Nicole J. Olynk Widmar

Committee Member 2

Michael A. Steele

Committee Member 3

Patrick A. Zollner

Abstract

Seed attributes are important predictors of rodent foraging behaviors. I examined the role of seed attributes in eastern gray squirrel (Sciurus carolinensis) foraging behavior from an evolutionary, economic, ecological and biochemical perspective. From an evolutionary perspective (chapter 2), I found that squirrel foraging behaviors are influenced by a combination of phylogenetically conserved and evolutionarily labile seed traits, which supports a diffuse coevolutionary relationship between hardwood trees and squirrels and provides indirect evidence supporting the Janzen-Connell and handling time hypotheses. From an economic perspective (chapter 3), I found that eastern gray squirrels are homogenous with respect to their preferences for seed attributes, which is likely due to natural selection favoring caching of specific seeds in the fall. I also provide evidence that squirrels trade between 3 attributes when selecting seeds for caching, which results in a variety of seed types being cached. In contrast, squirrels trade between 2 attributes when selecting seeds for consumption, which leads to fewer seed types being consumed in the fall. From an ecological context perspective (chapter 4), I provide evidence of seed traits interacting with relative seed availability to predict caching. Specifically, when seeds of different caching value (i.e., utility) were paired, relative frequency of availability played a minimal role in predicting seed caching. In contrast when seeds of similar caching utility were paired, relative frequency of availability significantly influenced probability of seed selection for caching. From a biochemical perspective (chapter 5), I identified biochemical and anatomical changes at the cellular level associated with radicle dormancy that serve as a signal of lack of dormancy to eastern gray squirrels. In combination, my dissertation chapters support the existence of complex reciprocal evolutionary effects between hardwood trees and eastern gray squirrels.

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